Noise shaping is a well-known technique typically used in digital signal processing applications, often in conjunction with dithering, as part of the quantization of a digital signal for increasing a signal-to-noise ratio (SNR) of the resultant signal. Noise shaping achieves this by changing a spectral shape of the error introduced by the quantization process, such that the noise power in the frequency range of interest is reduced to a lower level and this noise power is correspondingly pushed to a higher level outside of the frequency range of interest where such noise is less perceptible.
Digital radio frequency (RF) systems using shaped quantization noise can achieve higher efficiency when switched at lower sampling rates. If sample rates are too low, however, an image of the desired carrier signal may appear in or near the desired signal band. When this occurs, expensive lossy reflective or absorptive filters are required to remove the undesired image component.